Amniocentesis can be performed from 15 gestational weeks (15 + 0), before 15 weeks an alternative invasive test called CVS (chorionic villus sampling) is recommended. Amniocentesis involves passing a thin needle into the uterus in order to obtain a small volume of amniotic fluid. Movement of the needle is carefully controlled by ultrasound scan. A sample of amniotic fluid (about 18 ml) is then sent for genetic analysis to a cytogenetic laboratory. Because a needle needs to be inserted into the uterine cavity, amniocentesis is an invasive test and slightly increases the risk of miscarriage (by about 0.5%). The procedure itself is not more painful than taking a blood sample. After the procedure you may experience some abdominal discomfort or period-like pain, but this should resolve within 1 – 2 days. You may find it helpful to take a basic painkiller such as paracetamol.
Initial results of the presence of the most frequent chromosomal defects are available within 2 working days after the procedure, complete results available usually within 2 weeks. You will be informed of the first results by a phone call from us or from the clinical geneticists. Complete results should be passed to you at counselling so are sent to a clinical geneticist, who will also be able explain them fully to you.